Question

 

Q1. Write down the equation of the regression straight line (the least-squares line)

Q2. For an increase of 1 mg of fertiliser applied, what is the average change in the wet weight of maize plants?

Q3.​​​​​​ ​How are the two variables associated with each other? (Answer in 1 or 2 sentences)
Q4. Determine the average weight of plants grown with 100mg of fertiliser applied. (round up your answer to 2 decimal places)
Q5. Determine the average weight of plants grown with 500mg of fertiliser applied. (round up your answer to 2 decimal places)

Fertiliser weight in mg
90
160
290
0
30
60
0
200
0
0
70
140
160
460
330
0
60
70
350
250
510
510
0
0
40
100
110
280
280
0
0
20
40
130
150
280
340
0
0
190
40
190
90
210
270
0
0
20
60
180
210
400
300
0
0
20
70
140
160
240

Plant weight in g
5.92
9.53
16.05
7.14
1.64
11.43
6.73
11.36
7.64
9.57
10.44
12.99
30.44
11.92
15.58
7.12
14.47
10.54
16.05
23.72
14.33
22.87
3.86
4.45
5.43
8.68
6.28
9.07
17.69
6.67
5.47
7.00
8.43
17.20
10.21
13.24
4.31
5.14
5.23
6.77
7.26
8.32
7.95
9.70
13.94
8.66
5.46
9.87
3.68
17.42
21.80
13.31
6.76
7.72
5.39
12.36
11.31
5.54
5.48
14.38

Answer 1

Q1. Write down the equation of the regression straight line (the least-squares line)

Step 1 - Put the data in excel as shown and arrange the variables as shown

Step 2 - Select the regression option from the data analysis tab

Step 3- Input the values as shown below.

Step 4 - The output is generated as follows.

The regression equation ( This equation is obtained from the coefficient of the regression output. Highlighted in green)

Plant weight in g (y) = 7.4019 + 0.02106 Fertiliser weight in mg(x)

Q2. For an increase of 1 mg of fertiliser applied, what is the average change in the wet weight of maize plants?

The average change in the weight of maize plants is 0.02106

Q3.​​​​​​ ​How are the two variables associated with each other? (Answer in 1 or 2 sentences)

Association between the two variables is signficantly. We look at the pvalue of the Ftest and find that it less than 0.05, hence we conclude that the model is signficant.

Q4. Determine the average weight of plants grown with 100mg of fertiliser applied. (round up your answer to 2 decimal places)
Plant weight in g (y) = 7.4019 + 0.02106 Fertiliser weight in mg(x)
Plant weight in g (y) = 7.4019 + 0.02106 (100)=9.5079

Q5. Determine the average weight of plants grown with 500mg of fertiliser applied. (round up your answer to 2 decimal places)

Plant weight in g (y) = 7.4019 + 0.02106 Fertiliser weight in mg(x)
Plant weight in g (y) = 7.4019 + 0.02106 (500) = 17.9319